Ten-year-old Macy Friday, front left, reacts as she looks back at her family after meeting Hillary Clinton, front right, as she campaigns for U.S. Sen. Mark Udall, D-Colo., back, during a stop in the newly-renovated Union Station in Denver on Monday, October 13, 2014. Clinton appeared at an event to raise money for Udall's current re-election campaign and then headed to Las Vegas for another appearance on Monday night. (Photo by David Zalubowski/AP Photo)

Enya Kim from the Natural History department at auctioneers Bonhams & Butterfields stands in front of one of the world's largest set of shark jaws comprised of about 180 fossil teeth from the prehistoric species, Carcharocles megalodon, which grew to the size of a school bus, at the Venetian Resort Hotel Casino September 30, 2009 in Las Vegas, Nevada. (Photo by Ethan Miller/Getty Images)

Dameon Harris of Nevada gets used to the controls of a bulldozer at Dig This October 27, 2011 in Las Vegas, Nevada. At Dig This, tourists take a short class and can then operate full-size hydraulic excavators and track-type bulldozers in a giant sandbox while being guided by instructors over headsets. (Photo by Ethan Miller/Getty Images)

A poster advertises the highly anticipated video game, “Call Of Duty: Modern Warfare 3” at a GameStop Corp. store November 6, 2011 in North Las Vegas, Nevada. Video game publisher Activision plans to release the eighth installment in the “Call of Duty” franchise at midnight on November 8. (Photo by Ethan Miller/Getty Images)

SI bodypaint model, soccer player Alex Morgan (L) attends SI Swimsuit On Location hosted by Haze Nightclub at the Aria Resort & Casino at CityCenter on February 15, 2012 in Las Vegas, Nevada. (Photo by Michael Loccisano/Getty Images for Sports Illustrated)

In this February 5, 2014 photo, Divaldo Aguiar, who plays the part of Pachencho, is carried in a mock coffin during the Burial of Pachencho celebration, through a cemetery in Santiago de Las Vegas, Cuba. Cuban villagers stage a mock funeral and burial of Pachencho, with a living man playing the part of Pachencho, in a boozy festival that has become an annual tradition in this small town near Havana, held each February 5 for the last 30 years. (Photo by Enric Marti/AP Photo)

Guillermo Rodriguez and Sports Illustrated Swimsuit Issue cover model Kate Upton arrive at Club SI Swimsuit hosted by the Pure Nightclub at Caesars Palace at the Pure Nightclub at Caesars Palace on February 16, 2012 in Las Vegas, Nevada. (Photo by Michael Loccisano/Getty Images for Sports Illustrated)

The Mike O'Callaghan–Pat Tillman Memorial Bridge is an arch bridge in the United States that spans the Colorado River between the states of Arizona and Nevada. The bridge is located within the Lake Mead National Recreation Area approximately 30 miles (48 km) southeast of Las Vegas, Nevada, and carries U.S. Route 93 over the Colorado River.